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U. S. Department of Justice 

Federal Bureau of Investigation 





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Handgun Wounding Factors and Effectiveness 

Special Agent UREY W. PATRICK 

July 14, 1989 

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Reproduced with Permission of the Author 


The selection of effective handgun ammunition for law enforcement is a critical and complex 
issue. It is critical because of that which is at stake when an officer is required to use his handgun to 
protect his own life or that of another. It is complex because of the target, a human being, is amazingly 
endurable and capable of sustaining phenomenal punishment while persisting in a determined course of 
action. The issue is made even more complex by the dearth of credible research and the wealth of 
uninformed opinion regarding what is commonly referred to as "stopping power". 

In reality, few people have conducted relevant research in this area, and fewer still have produced 
credible information that is useful for law enforcement agencies in making informed decisions. 

This article brings together what is believed to be the most credible information regarding wound 
ballistics. It cuts through the haze and confusion, and provides common-sense, scientifically supportable, 
principles by which the effectiveness of law enforcement ammunition may be measured. It is written 
clearly and concisely. The content is credible and practical. The information contained in this article is not 
offered as the final word on wound ballistics. It is, however, an important contribution to what should be 
an ongoing discussion of this most important of issues. 

John C. Hall 
Unit Chief 

Firearms Training Unit 


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The handgun is the primary weapon in law enforcement. It is the one weapon any officer or agent 
can be expected to have available whenever needed. Its purpose is to apply deadly force to not only 
protect the life of the officer and the lives of others, but to prevent serious physical harm to them as well . 1 
When an officer shoots a subject, it is done with the explicit intention of immediately incapacitating that 
subject in order to stop whatever threat to life or physical safety is posed by the subject. Immediate 
incapacitation is defined as the sudden 2 physical or mental inability to pose any further risk or injury to 

The concept of immediate incapacitation is the only goal of any law enforcement shooting and is 
the underlying rationale for decisions regarding weapons, ammunition, calibers and training. While this 
concept is subject to conflicting theories, widely held misconceptions, and varied opinions generally 
distorted by personal experiences, it is critical to the analysis and selection of weapons, ammunition and 
calibers for use by law enforcement officers . 3 ’ 4 

1 FBI Deadly Force Policy. 

2 Ideally, immediate incapacitation occurs instantaneously. 

3 Fackler, M.L, MD: 'What’s Wrong with the Wound Ballistics Literature, and Why", Letterman Army Institute of 
Research, Presidio of San Francisco, CA, Report No. 239, July, 1987. 

4 Fackler, M.L., M.D., Director, Wound Ballistics Laboratory, Letterman Army Institute of Research, Presidio of San 
Francisco, CA, letter: "Bullet Performance Misconceptions", International Defense Review 3; 369-370, 1987. 


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Shot placement is an important, and often cited, consideration regarding the suitability of 
weapons and ammunition. However, considerations of caliber are equally important and cannot be 
ignored. For example, a bullet through the central nervous system with any caliber of ammunition is 
likely to be immediately incapacitating.' Even a .22 rimfire penetrating the brain will cause immediate 
incapacitation in most cases. Obviously, this does not mean the law enforcement agency should issue .22 
rimfires and train for head shots as the primary target. The realities of shooting incidents prohibit such a 

Few, if any, shooting incidents will present the officer with an opportunity to take a careful, 
precisely aimed shot at the subject’s head. Rather, shootings are characterized by their sudden, 
unexpected occurrence; by rapid and unpredictable movement of both officer and adversary; by limited 
and partial target opportunities; by poor light and unforeseen obstacles; and by the life or death stress of 
sudden, close, personal violence. Training is quite properly oriented towards "center of mass" shooting. 
That is to say, the officer is trained to shoot at the center of whatever is presented for a target. Proper shot 
placement is a hit in the center of that part of the adversary which is presented, regardless of anatomy or 

A review of law enforcement shootings clearly suggests that regardless of the number of rounds 
fired in a shooting, most of the time only one or two solid torso hits on the adversary can be expected. 

This expectation is realistic because of the nature of shooting incidents and the extreme difficulty of 
shooting a handgun with precision under such dire conditions. The probability of multiple hits with a 
handgun is not high. Experienced officers implicitly recognize that fact, and when potential violence is 
reasonably anticipated, their preparations are characterized by obtaining as many shoulder weapons as 
possible. Since most shootings are not anticipated, the officer involved cannot be prepared in advance 
with heavier armament. As a corollary tactical principle, no law enforcement officer should ever plan to 
meet an expected attack armed only with a handgun. 

The handgun is the primary weapon for defense against unexpected attack. Nevertheless, a 
majority of shootings occur in manners and circumstances in which the officer either does not have any 
other weapon available, or cannot get to it. The handgun must be relied upon, and must prevail. Given the 
idea that one or two torso hits can be reasonably expected in a handgun shooting incident, the ammunition 
used must maximize the likelihood of immediate incapacitation. 


Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September, 1987. Conclusion of the 


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In order to predict the likelihood of incapacitation with any handgun round, an understanding of 
the mechanics of wounding is necessary. There are four components of projectile wounding. 6 Not all of 
these components relate to incapacitation, but each of them must be considered. They are: 

(1) Penetration. The tissue through which the projectile passes, and which it disrupts or 

(2) Permanent Cavity. The volume of space once occupied by tissue that has been 
destroyed by the passage of the projectile. This is a function of penetration and the frontal 
area of the projectile. Quite simply, it is the hole left by the passage of the bullet. 

(3) Temporary Cavity. The expansion of the permanent cavity by stretching due to the 
transfer of kinetic energy during the projectile’s passage. 

(4) Fragmentation. Projectile pieces or secondary fragments of bone which are impelled 
outward from the permanent cavity and may sever muscle tissues, blood vessels, etc., 
apart from the permanent cavity. 7 ’ 8 Fragmentation is not necessarily present in every 
projectile wound. It may, or may not, occur and can be considered a secondary effect. 9 

Projectiles incapacitate by damaging or destroying the central nervous system, or by causing lethal blood 
loss. To the extent the wound components cause or increase the effects of these two mechanisms, the 
likelihood of incapacitation increases. Because of the impracticality of training for head shots, this 
examination of handgun wounding relative to law enforcement use is focused upon torso wounds and the 
probable results. 

6 Josselson, A., MD, Armed Forces Institute of Pathology, Walter Reed Army Medical Center, Washington, D.C., 
lecture series to FBI National Academy students, 1982-1983. 

7 DiMaio, V.J.M.: Gunshot Wounds. Elsevier Science Publishing Company, New York, NY, 1987: Chapter 3, Wound 
Ballistics: 41-49. 

8 Fackler, M.L, Malinowski, J.A.: "The Wound Profile: A Visual Method for Quantifying Gunshot Wound 
Components", Journal of Trauma 25, 522-529, 1985. 

9 Fackler, M.L., MD: "Missile Caused Wounds", Letterman Army Institute of Research, Presidio of San Francisco, 
CA, Report No. 231, April 1987. 


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All handgun wounds will combine the components of penetration, permanent cavity, and 
temporary cavity to a greater or lesser degree. Fragmentation, on the other hand, does not reliably occur in 
handgun wounds due to the relatively low velocities of handgun bullets. Fragmentation occurs reliably in 
high velocity projectile wounds (impact velocity in excess of 2000 feet per second) inflicted by soft or 
hollow point bullets. 10 In such a case, the permanent cavity is stretched so far, and so fast, that tearing and 
rupturing can occur in tissues surrounding the wound channel which were weakened by fragmentation 
damage. 11 ' 12 It can significantly increase damage 13 in rifle bullet wounds. 

Since the highest handgun velocities generally do not exceed 1400-1500 feet per second (fps) at 
the muzzle, reliable fragmentation could only be achieved by constructing a bullet so frangible as to 
eliminate any reasonable penetration. Unfortunately, such a bullet will break up too fast to penetrate to 
vital organs. The best example is the Glaser Safety Slug, a projectile designed to break up on impact and 
generate a large but shallow temporary cavity. Fackler, when asked to estimate the survival time of 
someone shot in the front mid-abdomen with a Glaser slug, responded, "About three days, and the cause 
of death would be peritonitis." 14 

In cases where some fragmentation has occurred in handgun wounds, the bullet fragments are 
generally found within one centimeter of the permanent cavity. "The velocity of pistol bullets, even of the 
new high-velocity loadings, is insufficient to cause the shedding of lead fragments seen with rifle 
bullets." 15 It is obvious that any additional wounding effect caused by such fragmentation in a handgun 
wound is inconsequential. 

Of the remaining factors, temporary cavity is frequently, and grossly, overrated as a wounding 
factor when analyzing wounds. 16 Nevertheless, historically it has been used in some cases as the primary 
means of assessing the wounding effectiveness of bullets. 

10 Josselson, A., MD, Armed Forces Institute of Pathology, Walter Reed Army Medical Center, Washington, D.C., 
lecture series to FBI National Academy students, 1982-1983. 

11 Fackler, M.L, MD: "Ballistic Injury", Annals of Emergency Medicine 15: 12 December 1986. 

12 Fackler, M.L., Surinchak, J.S., Malinowski, J.A.; "Bullet Fragmentation: A Major Cause of Tissue 
Disruption", Journal of Trauma 24: 35-39, 1984. 

13 Fragmenting rifle bullets in some of Fackler's experiments have caused damage 9 centimeters from the 
permanent cavity. Such remote damage is not found in handgun wounds. Fackler stated at the Workshop that 
when a handgun bullet does fragment the pieces typically are found within one centimeter of the wound track. 

14 Fackler, M.L., M.D., Director, Wound Ballistics Laboratory, Letterman Army Institute of Research, Presidio of San 
Francisco, CA, letter: "Bullet Performance Misconceptions", International Defense Review 3; 369-370, 1987. 

15 DiMaio, V.J.M.: Gunshot Wounds. Elsevier Science Publishing Company, New York, NY 1987, page 47. 

16 Lindsay, Douglas, MD: "The Idolatry of Velocity, or Lies, Damn Lies, and Ballistics", Journal of Trauma 20: 1068- 
1069, 1980. 


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The most notable example is the Relative Incapacitation Index (RII) which resulted from a study 
of handgun effectiveness sponsored by the Law Enforcement Assistance Administration (LEAA). In this 
study, the assumption was made that the greater the temporary cavity, the greater the wounding effect of 
the round. This assumption was based on a prior assumption that the tissue bounded by the temporary 
cavity was damaged or destroyed . 17 

In the LEAA study, virtually every handgun round available to law enforcement was tested. The 
temporary cavity was measured, and the rounds were ranked based on the results. The depth of 
penetration and the permanent cavity were ignored. The result according to the Rll is that a bullet which 
causes a large but shallow temporary cavity is a better incapacitater than a bullet which causes a smaller 
temporary cavity with deep penetration. 

Such conclusions ignore the factors of penetration and permanent cavity. Since vital organs are 
located deep within the body, it should be obvious that to ignore penetration and permanent cavity is to 
ignore the only proven means of damaging or disrupting vital organs. 

Further, the temporary cavity is caused by the tissue being stretched away from the permanent 
cavity, not being destroyed. By definition, a cavity is a space 18 in which nothing exists. A temporary 
cavity is only a temporary space caused by tissue being pushed aside. That same space then disappears 
when the tissue returns to its original configuration. 

Frequently, forensic pathologists cannot distinguish the wound track caused by a hollow point 
bullet (large temporary cavity) from that caused by a solid bullet (very small temporary cavity). There 
may be no physical difference in the wounds. If there is no fragmentation, remote damage due to 
temporary cavitation may be minor even with high velocity rifle projectiles . 19 Even those who have 
espoused the significance of temporary cavity agree that it is not a factor in handgun wounds: 

"In the case of low-velocity missiles, e.g., pistol bullets, the bullet produces a direct path of 
destruction with very little lateral extension within the surrounding tissues. Only a small 
temporary cavity is produced. To cause significant injuries to a structure, a pistol bullet 
must strike that structure directly. The amount of kinetic energy lost in tissue by a pistol 
bullet is insufficient to cause remote injuries produced by a high velocity rifle bullet ." 20 

17 Bruchey, W.J., Frank, D.E.: Police Handgun Ammunition Incapacitation Effects. National Institute of Justice 
Report 100-83. Washington, D.C., U.S. Government Printing Office, 1984, Vol. 1: Evaluation . 

18 Webster's Ninth New Collegiate Dictionary. Merriam-Webster Inc., Springfield MA, 1986: "An unfilled space within 
a mass." 

19 Fackler, M.L., Surinchak, J.S., Malinowski, J.A.; "Bullet Fragmentation: A Major Cause of Tissue 
Disruption", Journal of Trauma 24: 35-39, 1984. 

20 DiMaio, V.J.M.: Gunshot Wounds. Elsevier Science Publishing Company, New York, NY 1987, page 42. 


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The reason is that most tissue in the human target is elastic in nature. Muscle, blood vessels, lung, 
bowels, all are capable of substantial stretching with minimal damage. Studies have shown that the 
outward velocity of the tissues in which the temporary cavity forms is no more than one tenth of the 
velocity of the projectile. 21 This is well within the elasticity limits of tissue such as muscle, blood vessels, 
and lungs, Only inelastic tissue like liver, or the extremely fragile tissues of the brain, would show 
significant damage due to temporary cavitation. 22 

The tissue disruption caused by a handgun bullet is limited to two mechanisms. The first, or crush 
mechanism is the hole the bullet makes passing through the tissue. The second, or stretch mechanism is 
the temporary cavity formed by the tissues being driven outward in a radial direction away from the path 
of the bullet. Of the two, the crush mechanism, the result of penetration and permanent cavity, is the only 
handgun wounding mechanism which damages tissue. 23 To cause significant injuries to a structure within 
the body using a handgun, the bullet must penetrate the structure. Temporary cavity has no reliable 
wounding effect in elastic body tissues. Temporary cavitation is nothing more than a stretch of the tissues, 
generally no larger than 10 times the bullet diameter (in handgun calibers), and elastic tissues sustain 
little, if any, residual damage. 24,25 ’ 26 

21 Fackler, M.L., Surinchak, J.S., Malinowski, J.A.; "Bullet Fragmentation: A Major Cause of Tissue 
Disruption", Journal of Trauma 24: 35-39, 1984. 

22 Fackler, M.L, MD: "Ballistic Injury", Annals of Emergency Medicine 15: 12 December 1986. 

23 Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September, 1987. Conclusion of the 

24 Fackler, M.L, MD: "Ballistic Injury", Annals of Emergency Medicine 15: 12 December 1986. 

25 Fackler, M.L, Malinowski, J.A.: "The Wound Profile: A Visual Method for Quantifying Gunshot Wound 
Components", Journal of Trauma 25: 522-529, 1985. 

26 Lindsay, Douglas, MD: "The Idolatry of Velocity, or Lies, Damn Lies, and Ballistics", Journal of Trauma 20: 1068- 
1069, 1980. 


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With the exceptions of hits to the brain or upper spinal cord, the concept of reliable and 
reproducible immediate incapacitation of the human target by gunshot wounds to the torso is a myth. 27 
The human target is a complex and durable one. A wide variety of psychological, physical, and 
physiological factors exist, all of them pertinent to the probability of incapacitation. However, except for 
the location of the wound and the amount of tissue destroyed, none of the factors are within the control of 
the law enforcement officer. 

Physiologically, a determined adversary can be stopped reliably and immediately only by a shot 
that disrupts the brain or upper spinal cord. Failing a hit to the central nervous system, massive bleeding 
from holes in the heart or major blood vessels of the torso causing circulatory collapse is the only other 
way to force incapacitation upon an adversary, and this takes time. For example, there is sufficient 
oxygen within the brain to support full, voluntary action for 10-15 seconds after the heart has been 
destroyed. 28 

In fact, physiological factors may actually play a relatively minor role in achieving rapid 
incapacitation. Barring central nervous system hits, there is no physiological reason for an individual to 
be incapacitated by even a fatal wound, until blood loss is sufficient to drop blood pressure and/or the 
brain is deprived of oxygen. The effects of pain, which could contribute greatly to incapacitation, are 
commonly delayed in the aftermath of serious injury such as a gunshot wound. The body engages survival 
patterns, the well known "fight or flight" syndrome. Pain is irrelevant to survival and is commonly 
suppressed until some time later. In order to be a factor, pain must first be perceived, and second must 
cause an emotional response. In many individuals, pain is ignored even when perceived, or the response is 
anger and increased resistance, not surrender. 

Psychological factors are probably the most important relative to achieving rapid incapacitation 
from a gunshot wound to the torso. Awareness of the injury (often delayed by the suppression of pain); 
fear of injury, death, blood, or pain; intimidation by the weapon or the act of being shot; preconceived 
notions of what people do when they are shot; or the simple desire to quit can all lead to rapid 
incapacitation even from minor wounds. However, psychological factors are also the primary cause of 
incapacitation failures. 

The individual may be unaware of the wound and thus has no stimuli to force a reaction. Strong 
will, survival instinct, or sheer emotion such as rage or hate can keep a grievously injured individual 
fighting, as is common on the battlefield and in the street. The effects of chemicals can be powerful 
stimuli preventing incapacitation. Adrenaline alone can be sufficient to keep a mortally wounded 
adversary functioning. Stimulants, anesthetics, pain killers, or tranquilizers can all prevent incapacitation 
by suppressing pain, awareness of the injury, or eliminating any concerns over the injury. Drugs such as 
cocaine, PCP, and heroin are disassociative in nature. One of their effects is that the individual "exists" 
outside of his body. He sees and experiences what happens to his body, but as an outside observer who 
can be unaffected by it yet continue to use the body as a tool for fighting or resisting. 

27 Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September 1987. Conclusion of the 

28 Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September 1987. Conclusion of the 

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Psychological factors such as energy deposit, momentum transfer, size of temporary cavity or 
calculations such as the Rll are irrelevant or erroneous. The impact of the bullet upon the body is no more 
than the recoil of the weapon. The ratio of bullet mass to target mass is too extreme. 

The often referred to "knock-down power" implies the ability of a bullet to move its target. This is 
nothing more than momentum of the bullet. It is the transfer of momentum that will cause a target to 
move in response to the blow received. "Isaac Newton proved this to be the case mathematically in the 
17 th Century, and Benjamin Robins verified it experimentally through the invention and use of the 
ballistic pendulum to determine muzzle velocity by measurement of the pendulum motion." 29 

Goddard amply proves the fallacy of "knock-down power" by calculating the heights (and 
resultant velocities) from which a one pound weight and a ten pound weight must be dropped to equal the 
momentum of 9mm and .45ACP projectiles at muzzle velocities, respectively. The results are revealing. 

In order to equal the impact of a 9mm bullet at its muzzle velocity, a one pound weight must be dropped 
from a height of 5.96 feet, achieving a velocity of 19.6 fps. To equal the impact of a .45ACP bullet, the 
one pound weight needs a velocity of 27. 1 fps and must be dropped from a height of 1 1 .4 feet. A ten 
pound weight equals the impact of a 9mm bullet when dropped from a height of 0.72 inches (velocity 
attained is 1.96 fps), and equals the impact of a .45 when dropped from 1.37 inches (achieving a velocity 
of 2.71 fps). 30 

A bullet simply cannot knock a man down. If it had the energy to do so, then equal energy would 
be applied against the shooter and he too would be knocked down. This is simple physics, and has been 
known for hundreds of years. 31 The amount of energy deposited in the body by a bullet is approximately 
equivalent to being hit with a baseball. 32 Tissue damage is the only physical link to incapacitation within 
the desired time frame, i.e., instantaneously. 

The human target can be reliably incapacitated only by disrupting or destroying the brain or upper 
spinal cord. Absent that, incapacitation is subject to a host of variables, the most important of which are 
beyond the control of the shooter. Incapacitation becomes an eventual event, not necessarily an immediate 
one. If the psychological factors which can contribute to incapacitation are present, even a minor wound 
can be immediately incapacitating. If they are not present, incapacitation can be significantly delayed 
even with major, unsurvivable wounds. 

29 Goddard, Stanley: "Some Issues for Consideration in Choosing Between 9mm and .45ACP Handguns", Battelle 
Labs, Ballistic Sciences, Ordnance Systems and Technology Section, Columbus, OH, presented to the FBI 
Academy, 2/16/88, pages 3-4. 

30 Goddard, Stanley: "Some Issues for Consideration in Choosing Between 9mm and .45ACP Handguns", Battelle 
Labs, Ballistic Sciences, Ordnance Systems and Technology Section, Columbus, OH, presented to the FBI 
Academy, 2/16/88, pages 3-4. 

31 Newton, Sir Isaac, Principia Mathematica. 1687, in which are stated Newton's Laws of Motion. The Second Law 
of Motion states that a body will accelerate, or change its speed, at a rate that is proportional to the force acting 
upon it. In simpler terms, for every action there is an equal but opposite reaction. The acceleration will of course 
be in inverse proportion to the mass of the body. For example, the same force acting upon a body of twice the 
mass will produce exactly half the acceleration. 

32 Lindsay, Douglas, MD, presentation to the Wound Ballistics Workshop, Quantico, VA, 1987. 


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Field results are a collection of individualistic reactions on the part of each person shot which can 
be analyzed and reported as percentages. However, no individual responds as a percentage, but as an all 
or none phenomenon which the officer cannot possibly predict, and which may provide misleading data 
upon which to predict ammunition performance. 


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The critical wounding components for handgun ammunition, in order of importance, are 
penetration and permanent cavity . 33 The bullet must penetrate sufficiently to pass through vital organs 
and be able to do so from less than optimal angles. For example, a shot from the side through an arm must 
penetrate at least 10-12 inches to pass through the heart. A bullet fired from the front through the 
abdomen must penetrate about 7 inches in a slender adult just to reach the major blood vessels in the back 
of the abdominal cavity. Penetration must be sufficiently deep to reach and pass through vital organs, and 
the permanent cavity must be large enough to maximize tissue destruction and consequent hemorrhaging. 

Several design approaches have been made in handgun ammunition which are intended to 
increase the wounding effectiveness of the bullet. Most notable of these is the use of a hollow point bullet 
designed to expand on impact. 

Expansion accomplishes several things. On the positive side, it increases the frontal area of the 
bullet and thereby increases the amount of tissue disintegrated in the bullet’s path. On the negative side, 
expansion limits penetration. It can prevent the bullet from penetrating to vital organs, especially if the 
projectile is of relatively light mass and the penetration must be through several inches of fat, muscle, or 
clothing. 34 

Increased bullet mass will increase penetration. Increased velocity will increase penetration but 
only until the bullet begins to deform, at which point increased velocity decreases penetration. Permanent 
cavity can be increased by the use of expanding bullets, and/or larger diameter bullets, which have 
adequate penetration. However, in no case should selection of a bullet be made where bullet expansion is 
necessary to achieve desired performance. 35 Handgun bullets expand in the human target only 60-70% of 
the time at best. Damage to the hollow point by hitting bone, glass, or other intervening obstacles can 
prevent expansion. Clothing fibers can wrap the nose of the bullet in a cocoon like manner and prevent 
expansion. Insufficient impact velocity caused by short barrels and/or longer range will prevent 
expansion, as will simple manufacturing variations. Expansion must never be the basis for bullet 
selection, but considered a bonus when, and if, it occurs. Bullet selection should be determined based on 
penetration first, and the unexpanded diameter of the bullet second, as that is all the shooter can reliably 

It is essential to bear in mind that the single most critical factor remains penetration. While 
penetration up to 18 inches is preferable, a handgun bullet MUST reliably penetrate 12 inches of soft 
body tissue at a minimum, regardless of whether it expands or not. If the bullet does not reliably penetrate 
to these depths, it is not an effective bullet for law enforcement use. 36 

33 Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September, 1987. Conclusion of the 

34 Jones, J.A.: Police Flandgun Ammunition. Southwestern Institute of Forensic Sciences at Dallas, 523D Medical 
Center Drive, Dallas, TX, 1985. 

35 Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September, 1987. Conclusion of the 

36 Wound Ballistic Workshop: "9mm vs. .45 Auto", FBI Academy, Quantico, VA, September 1987. Conclusion of the 


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Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. 
It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead 
to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified. 

An issue that must be addressed is the fear of over penetration widely expressed on the part of law 
enforcement. The concern that a bullet would pass through the body of a subject and injure an innocent 
bystander is clearly exaggerated. Any review of law enforcement shootings will reveal that the great 
majority of shots fired by officers do not hit any subjects at all. It should be obvious that the relatively 
few shots that do hit a subject are not somehow more dangerous to bystanders than the shots that miss the 
subject entirely. 

Also, a bullet that completely penetrates a subject will give up a great deal of energy doing so. 

The skin on the exit side of the body is tough and flexible. Experiments have shown that it has the same 
resistance to bullet passage as approximately four inches of muscle tissue . 37 

Choosing a bullet because of relatively shallow penetration will seriously compromise weapon 
effectiveness, and needlessly endanger the lives of the law enforcement officers using it. No law 
enforcement officer has lost his life because a bullet over penetrated his adversary, and virtually none 
have ever been sued for hitting an innocent bystander through an adversary. On the other hand, tragically 
large numbers of officers have been killed because their bullets did not penetrate deeply enough. 

37 Fackler, M.L., M.D., Director, Wound Ballistics Laboratory, Letterman Army Institute of Research, Presidio of San 
Francisco, CA, letter: "Bullet Performance Misconceptions", International Defense Review 3; 369-370, 1987. 


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There is no valid, scientific analysis of actual shooting results in existence, or being pursued to 
date. It is an unfortunate vacuum because a wealth of data exists, and new data is being sadly generated 
every day. There are some well publicized, so called analyses of shooting incidents being promoted, 
however, they are greatly flawed. Conclusions are reached based on samples so small that they are 
meaningless. The author of one, for example, extols the virtues of his favorite cartridge because he has 
collected ten cases of one shot stops with it. 38 Preconceived notions are made the basic assumptions on 
which shootings are categorized. Shooting incidents are selectively added to the "data base" with no 
indication of how many may have been passed over or why. There is no correlation between hits, results, 
and the location of the hits upon vital organs. 

It would be interesting to trace a life-sized anatomical drawing on the back of a target, fire 20 
rounds at the "center of mass" of the front, then count how many of these optimal, center of mass hits 
actually struck the heart, aorta, vena cava, or liver. 39 It is rapid hemorrhage from these organs that will 
best increase the likelihood of incapacitation. Yet nowhere in the popular press extolling these studies of 
real shootings are we told what the bullets hit. 

These so called studies are further promoted as being somehow better and more valid than the 
work being done by trained researchers, surgeons and forensic labs. They disparage laboratory stuff, 
claiming that the "street" is the real laboratory and their collection of results from the street is the real 
measure of caliber effectiveness, as interpreted by them, of course. Yet their data from the street is 
collected haphazardly, lacking scientific method and controls, with no noticeable attempt to verify the less 
than reliable accounts of the participants with actual investigative or forensic reports. Cases are 
subjectively selected (how many are not included because they do not fit the assumptions made?). The 
numbers of cases cited are statistically meaningless, and the underlying assumptions upon which the 
collection of information and its interpretation are based are themselves based on myths such as knock- 
down power, energy transfer, hydrostatic shock, or the temporary cavity methodology of flawed work 
such as RII. 

Further, it appears that many people are predisposed to fall down when shot. This phenomenon is 
independent of caliber, bullet, or hit location, and is beyond the control of the shooter. It can only be 
proven in the act, not predicted. It requires only two factors to be effected: a shot and cognition of being 
shot by the target. Lacking either one, people are not at all predisposed to fall down and don’t. Given this 
predisposition, the choice of caliber and bullet is essentially irrelevant. People largely fall down when 
shot, and the apparent predisposition to do so exists with equal force among the good guys as among the 
bad. The causative factors are most likely psychological in origin. Thousands of books, movies and 
television shows have educated the general population that when shot, one is supposed to fall down. 

38 He defines a one shot stop as one in which the subject dropped, gave up, or did not run more than 10 feet. 

39 This exercise was suggested by Dr. Martin L. Fackler, U.S. Army Wound Ballistics Laboratory, Letterman Army 
Institute of Research, San Francisco, California, as a way to demonstrate the problematical results of even the 
best results sought in training, i.e., shots to the center of mass of a target. It illustrates the very small actually 
critical areas within the relatively vast mass of the human target. 


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The problem, and the reason for seeking a better cartridge for incapacitation, is that individual 
who is not predisposed to fall down. Or the one who is simply unaware of having been shot by virtue of 
alcohol, adrenaline, narcotics, or the simple fact that in most cases of grievous injury the body suppresses 
pain for a period of time. Lacking pain, there may be no physiological effect of being shot that can make 
one aware of the wound. Thus the real problem: if such an individual is threatening one’s life, how best to 
compel him to stop by shooting him? 

The factors governing incapacitation of the human target are many, and variable. The actual 
destruction caused by any small arms projectile is too small in magnitude relative to the mass and 
complexity of the target. If a bullet destroys about 2 ounces of tissue in its passage through the body, that 
represents 0.07 of one percent of the mass of a 180 pound man. Unless the tissue destroyed is located 
within the critical areas of the central nervous system, it is physiologically insufficient to force 
incapacitation upon the unwilling target. It may certainly prove to be lethal, but a body count is no 
evidence of incapacitation. Probably more people in this country have been killed by .22 rimfires than all 
other calibers combined, which, based on body count, would compel the use of ,22’s for self-defense. The 
more important question, which is sadly seldom asked, is what did the individual do when hit? 

There is a problem in trying to assess calibers by small numbers of shootings. For example, as has 
been done, if a number of shootings were collected in which only one hit was attained and the percentage 
of one shot stops was then calculated, it would appear to be a valid system. However, if a large number of 
people are predisposed to fall down, the actual caliber and bullet are irrelevant. What percentage of those 
stops were thus preordained by the target? How many of those targets were not at all disposed to fall 
down? How many multiple shot failures to stop occurred? What is the definition of a stop? What did the 
successful bullets hit and what did the unsuccessful bullets hit? How many failures were in the vital 
organs, and how many were not? How many of the successes? What is the number of the sample? How 
were the cases collected? What verifications were made to validate the information? How can the 
verifications be checked by independent investigation? 

Because of the extreme number of variables within the human target, and within shooting 
situations in general, even a hundred shootings is statistically insignificant. If anything can happen, then 
anything will happen, and it is just as likely to occur in your ten shootings as in ten shootings spread over 
a thousand incidents. Large sample populations are absolutely necessary. 

Here is an example that illustrates how erroneous small samples can be. 1 flipped a penny 20 
times, ft came up heads five times. A nickel flipped 20 times showed heads 8 times. A dime came up 
heads 10 times and a quarter 15 times. That means if heads is the desired result, a penny will give it to 
you 25% of the time, and nickel 40% of the time, a dime 50% of the time and a quarter 75% of the time. 

If you want heads, flip a quarter. If you want tails, flip a penny. But then I flipped the quarter another 20 
times and it showed heads 9 times - 45% of the time. Now this "study" would tell you that perhaps a dime 
was better for flipping heads. The whole thing is obviously wrong, but shows how small numbers lead to 
statistical lies. We know the odds of getting a head or tail are 50%, and larger numbers tend to prove it. 
Calculating the results for all 100 flips regardless of the coin used shows heads came up 48% of the time. 

The greater the number and complexity of the variables, the greater the sample needed to give 
meaningful information, and a coin toss has only one simple variable - it can land heads or it can land 
tails. The coin population is not complicated by a predisposition to fall one way or the other, by chemical 
stimuli, psychological factors, shot placement, bone or obstructive obstacles, etc.; all of which require 
even larger numbers to evidence real differences in effects. 


Reproduced with Permission of the Author 

Although no cartridge is certain to work all the time, surely some will work more often than 
others, and any edge is desirable in one’s self defense. This is simple logic. The incidence of failure to 
incapacitate will vary with the severity of the wound inflicted. 40 It is safe to assume that if a target is 
always 100% destroyed, then incapacitation will also occur 100% of the time. If 50% of the target is 
destroyed, incapacitation will occur less reliably. Failure to incapacitate is rare in such a case, but it can 
happen, and in fact has happened on the battlefield. Incapacitation is still less rare if 25% of the target is 
destroyed. Now the magnitude of bullet destruction is far less (less than 1% of the target) but the 
relationship is unavoidable. The round which destroys 0.07% of the target will incapacitate more often 
than the one which destroys 0.04%. However, only very large numbers of shooting incidents will prove it. 
The difference may be only 10 out of a thousand, but that difference is an edge, and that edge should be 
on the officer’s side because one of those ten may be the subject trying to kill him. 

To judge a caliber’s effectiveness, consider how many people hit with it failed to fall down and 
look at where they were hit. Of the successes and failures, analyze how many were hit in vital organs, 
rather than how many were killed or not, and correlate that with an account of exactly what they did when 
they were hit. Did they fall down, or did they run, fight, shoot, hide, crawl, stare, shrug, give up and 
surrender? ONLY falling down is good. All other reactions are failures to incapacitate, evidencing the 
ability to act with volition, and thus able to choose to continue to try to inflict harm. 

Those who disparage science and laboratory methods are either too short sighted or too bound by 
preconceived (or perhaps proprietary) notions to see the truth. The labs and scientists do not offer sure 
things. They offer a means of indexing the damage done by a bullet, understanding of the mechanics of 
damage caused by bullets and the actual effects on the body, and the basis for making an informed choice 
based on objective criteria and significant statistics. 

The differences between bullets may be small, but science can give us the means of identifying 
that difference. The result is the edge all of law enforcement should be looking for. It is true that the 
streets are the proving ground, but give me an idea of what you want to prove and I will give you ten 
shootings from the street to prove it. That is both easy, and irrelevant. If it can happen, it will happen. 

Any shooting incident is a unique event, unconstrained by any natural law or physical order to 
follow a predetermined sequence of events or end in predetermined results. What is needed is an edge that 
makes the good result more probable than the bad. Science will quantify the information needed to make 
the choice to gain that edge. Large numbers (thousands or more) from the street will provide the answer 
to the question "How much of an edge?". 41 Even if that edge is only 1%, it is not insignificant because 
the guy trying to kill you could be in that 1%, and you won’t know it until it is too late. 

40 Severity is a function of location, depth, and amount of tissue destroyed. 

41 The numbers can be held down to reasonable limits by a scientific approach that collects objective information 
from investigative and forensic sources and sorts it by vital organs struck and target reactions to being hit. The 
critical questions are what damage was done and what was the reaction of the adversary. 


Reproduced with Permission of the Author 


Physiologically, no caliber or bullet is certain to incapacitate any individual unless the brain is hit. 
Psychologically, some individuals can be incapacitated by minor or small caliber wounds. Those 
individuals who are stimulated by fear, adrenaline, drugs, alcohol, and/or sheer will and survival 
determination may not be incapacitated even if mortally wounded. 

The will to survive and to fight despite horrific damage to the body is commonplace on the 
battlefield, and on the street. Barring a hit to the brain, the only way to force incapacitation is to cause 
sufficient blood loss that the subject can no longer function, and that takes time. Even if the heart is 
instantly destroyed, there is sufficient oxygen in the brain to support full and complete voluntary action 
for 10-15 seconds. 

Kinetic energy does not wound. Temporary cavity does not wound. The much discussed "shock" 
of bullet impact is a fable and "knock down" power is a myth. The critical element is penetration. The 
bullet must pass through the large, blood bearing organs and be of sufficient diameter to promote rapid 
bleeding. Penetration less than 12 inches is too little, and, in the words of two of the participants in the 
1987 Wound Ballistics Workshop, "too little penetration will get you killed." 42 ’ 43 Given desirable and 
reliable penetration, the only way to increase bullet effectiveness is to increase the severity of the wound 
by increasing the size of hole made by the bullet. Any bullet which will not penetrate through vital organs 
from less than optimal angles is not acceptable. Of those that will penetrate, the edge is always with the 
bigger bullet. 44 

42 Fackler, M.L, MD, presentation to the Wound Ballistics Workshop, Quantico, VA, 1987. 

43 Smith, O'Brien C., IMD, presentation to the Wound Ballistics Workshop, Quantico, VA, 1987. 

44 Fackler, M.L, MD, presentation to the Wound Ballistics Workshop, Quantico, VA, 1987.